1. Field of the Invention
The present invention relates generally to commercial motor vehicles and more particularly to an automated vehicle inspection system providing the collection of selected data and prompting manual inspection and entry of other data to promote the generation of electronic inspection reports in an efficient and complete manner.
2. Description of the Problem
Commercial transport regulations provide for periodic inspection of, generation of inspection reports relating to, and documentation of maintenance on, commercial vehicles. Inspections include checking numerous operational aspects of the vehicle for conformity to normative operational standards, implementing a check off system for maintenance when indicated by inspection, as well as for scheduled maintenance, and validating the reports generated and keeping copies of the reports for a minimum time period.
Vehicle interactive on board computers (OBC) have been suggested in the art for use in implementing inspection programs directed to meeting regulations. The OBC suggested in U.S. Pat. No. 5,680,328 was preferably a personal or lap top computer, which is used for receiving data inputs from a driver or maintenance personnel as part of an inspection, and for providing for the collection of data from various sensors placed on the vehicle. However, the ""328 patent did not describe a mechanism for actually collecting data from vehicle sensors. The OBC may electronically store inspection reports, and provide copies of the same on a display or in hard copy form.
Contemporary designs for the control and management of vehicle components increasingly rely on methods derived from computer networking. Digital data is exchanged between component controllers over a common physical layer such as a twisted shielded pair of wires. Intelligible communication between two or more device controllers among a greater plurality of devices, all occurring over the common physical layer, depends upon the communicating devices being able to discriminate among messages they receive and to respond to those messages directed to them. Such methods are well known in the art and are part of the standards which the Society of Automotive Engineers (SAE) has published and continues to publish as part of the SAE J1939 protocol.
The J1939 protocol provides an open protocol and a definition of the performance requirements of the medium of the physical layer, but also allows for development of proprietary protocols. The SAE J1939 protocol is a specialized application of a controlled area network (CAN) and may be readily implemented utilizing commercial integrated circuits such as the C167 Integrated Circuit from Siemens of Germany.
The CAN protocol is an ISO standard (ISO 11898) for serial data communication, particularly aimed at automotive applications. The CAN standard includes a physical layer (including the data bus) and a data-link layer, which define useful message types, arbitration rules for bus access and methods for fault detection and fault confinement. The physical layer uses differential transmission on a twisted pair wire bus. A non-destructive bitwise arbitration is used to control access to the bus. Messages are small, at most eight bytes, and are protected by checksum error detection. There is no explicit address in the messages, instead, each message carries a numeric value which controls its priority on the bus, and may also serve as an identification of the contents of the message. CAN offers an error handling scheme that results in retransmitted messages when they are not properly received. CAN also provides means for removing faulty nodes from the bus. CAN further adds the capability of supporting what are termed xe2x80x9chigher layer protocolsxe2x80x9d for standardizing startup procedures including bit rate setting, distributing addresses among participating nodes or kinds of messages, determining the layout of the messages and routines for error handling on the system level.
Digital data communications over serial data paths are an effective technique for reducing the number of dedicated communication paths between the numerous switches, sensors, devices and gauges installed on the vehicles. Multiplexing the signals to and from local controllers and switches promises greater physical simplicity through displacing much of the vehicle wiring harness, reducing manufacturing costs, facilitating vehicle electrical load management, and enhancing system reliability.
It would be desirable to add intelligence to a vehicle controller area network conforming to the SAE J1939 standard to implement inspection regimens.
The invention integrates a general purpose computer with a controller area network to effect an inspection regimen through the controller area network. A convenient user interface is based on a combination of one or more devices, including handheld instruments, conventional displays, keypads, pucks and printers, and allows the driver to interact with the system. The computer provides storage for programs and processing power to implement test regimens in a logical order relating to completion of the inspection. Full integration of an OBC to an individual vehicle inspection procedure to promote efficiency and completeness, and to avoid possible damage to the vehicle, aids organization of the tasks called for by the inspection.
The substantially automated inspection system of the present invention works with a vehicle having an engine and with various vehicle systems, characterized by measurable operating variables. The system includes an electrical system controller, a data communications bus connected at one node to the electrical system controller, a plurality of sensors connected to the data communications bus for transmitting data relating to the operating variables to the electrical system controller, an user input/output interface, an on board computer connected to the user input/output interface and to the data communications bus, the on board computer including memory, and a vehicle inspection regimen stored in the memory and executable on the on board computer. The program provides means for checking fluid levels against one or more limits for various vehicle systems before engine start, means for prompting an operator to start the engine if the operating fluid levels meet applicable limits, and means for completing the vehicle inspection regimen after an engine start.
Additional effects, features and advantages will be apparent in the written description that follows.